Great progress has been achieved in building miniature non-scanning spectrometers, with no moving parts. Today's best non-scanning spectroscopy techniques are the Multi-Channel Dispersive Spectroscopy and the Holographic Fourier Transform Spectroscopy (HFTS) approaches, with a slight advantage for the latter one; the HFTS approach. A nice review study and a comparison between these techniques can be found in the article “Miniaturization of holographic Fourier-transform spectrometers”, by Nikolay I. Agladze and Albert J. Sievers, in APPLIED OPTICS, Vol. 43, No. 36, Dec. 20, 2004, as well as U.S. Pat. No. 6,930,781 B2, Aug. 16, 2005.
However, there is still a need for ultra-miniaturized aberration-free (i.e. comprising all reflective components) imaging spectrometers. And to be able to achieve the best possible performance, it is desired to build HFTSs fulfilling the previously mentioned requirements. There is also a need for two-dimensional (2D) instantaneous imaging spectrometers (also called staring hyperspectral cameras) that can capture the whole image cube in one shot, without the need for scanning.
Achieving these goals will widen the usage of spectroscopy considerably, and will also help in developing non-invasive techniques for numerous applications, such as telemedicine & telediagnosis, healthcare & medical diagnosis such as cancer & inflammation, mammography, endoscopy (even wireless capsule endoscopy), telesurgery, law medicine, stress detection, estimation of the concentration of Alcohol, Glucose, Cholesterol, Oxygen and other substances in the blood (can also be done by examining the skin), environmental monitoring, precession agriculture, forestry, food safety & quality measurement, food inspection, industrial inspection, veterinary, security, surveillance, law enforcement, defense, hazard detection, poisonous & harmful gases detection, monitoring of chemical reactions, mining, space & astronomy and Earth monitoring. Near-infrared and/or visible-light spectroscopy can be used for these applications.
In the case of using visible-light spectroscopy, it is also possible not only to perform precision color measurement and correction (colorimetry, e.g. color printing, paint manufacturing, etc) and to compensate for the illumination, but also to simulate a desired lighting environment and to add high quality light effects to the 2D hyperspectral image and finally convert it into a color image. It is also possible to segment and cut an object from one image and paste it into another image after adjusting the colors and the lighting effects to match the new image. As examples can be making an Indian elephant walk on the street in New York, or seeing him/herself exercising on Mars or under water among sharks. Another new field is making hyperspectral movies where lighting and colors can be adjusted afterwards as the producer or even the viewer wishes—one can make his/her own version of the movie at home. Therefore, perfect studio-lighting will not be necessary, saving time and money.
Recent studies have shown that Fourier-transform infrared (FTIR) spectro-imaging enables determination of the bio-distribution of several molecules of interest (such as carbohydrates, lipids, proteins) for tissue analysis without pre-analytical modification of the sample (such as staining) FTIR imaging can also reveal molecular structure information for protein secondary structure and fatty acyl chain peroxidation level. In other words, several cancer markers can be identified from FTIR tissue images, enabling accurate discrimination between healthy and tumour areas. Furthermore, FTIR imaging can provide unique chemical and morphological information about tissue status. Fast image acquisition techniques in the mid-infrared spectral range, makes it possible to analyze cerebral tumour exereses in delays compatible with neurosurgery. Accordingly, FTIR imaging will be taken into consideration for the development of new molecular histopathology tools.
In addition to the previously mentioned applications, achieving the spectrometer-design goals mentioned above is also desired within the application areas of Fourier Domain Confocal Optical Tomography, Fluorescence spectroscopy, Raman spectroscopy, IR (infrared) spectroscopy, X-ray spectroscopy, RF (radio frequency) spectroscopy, Microwave spectroscopy, Flame spectroscopy and Ultrasound spectroscopy.